multibuf(1)

NAME

multibuf - manage multiple volume archives

SYNOPSIS

multibuf [options] filename

DESCRIPTION

multibuf is a tape archive manager which provides the capability of extending a single logical archive over multiple physical media volumes.
multibuf is part of the KBackup package. See the documentation of KBackup for more information and the conditions of use.

OPTIONS

-r, --read

Set read mode. The archive is read from the device named in filename and written to stdout.

-w, --write (default)

Set write mode. The archive is read from stdin and written to the device named in filename.

-v, --verbose

Enable verbose progress reporting.

-m, --multibuf buffers

This enables real double-buffering using shared memory (Linux only) which can be used to keep a tape drive streaming continuously. The parameter is the number of shared buffers to use (at least 2).

-b, --blocksize byte_count (default = 1024)

This sets the minimal size of the data blocks used for the single write/read calls. Normally you should not change this.

-n, --nblocks block_count (default = 100, minimum = 5)

Use this option to change the size of the buffers used by multibuf.

-c, --command shell-command

Set command1, which is executed at end of medium. The default is "dialog --title with next volume? This command is expected to exit with a status of 0 to indicate that a retry should be performed.

-C, --command2 shell-command

Set command2, which is executed at beginning of medium. The default is "mt rewind </dev/tty >/dev/tty". The exit status of this command is not checked.

-R, --retry-command shell-command

Set command to execute when finding wrong sequence number. The default is "dialog --title "KBackup's MultiBuf" --yesno "Detected wrong sequence number. Retry?" 6 50 </dev/tty >/dev/tty". This command is expected to exit with a status of 0 to indicate that a retry should be performed.

-1, --end-only

Only execute command at end of media. This option disables command2 processing.

-2, --begin-and-end (default)

Exeute commands at end and begin of media. This option enables command2 processing.

-s, --settings

Display settings.

-x, --exit

Exit after processing options (for testing).

-h, --header

Add header/sequence information to data. This writes media headers with volume sequencing and block sizing information when writing an archive, or utilizes these headers when reading an archive.

-E, --no-endmarker

Do not use an endmarker. This disables archive writing of archive endmarkers when writing an an archive, and disables checking for these endmarkers when reading an archive.

-F, --file-endmarker

Write endmarker as a file on a mounted medium, or expect such an endmarker when reading from a mounted medium.

-D, --disable-filemark-fix

For debugging purpose only.

-V, --version

Print version information to stderr.

EXIT STATUS

0=success, 1=read error, 2=write error, 3=wrong sequence

EXAMPLE

You can use multibuf without KBackup. An example:
tar czvf - | multibuf -w -m 10 /dev/tape
This will write a tar file using double buffering and possibly spanning multiple physical volumes.

BUGS

multibuf uses the system(3) function internally. See the system(3) man page for caveats regarding the use of this function in setuid and setgid programs.

SEE ALSO

dialog(1)
kbackup(1)
mt(1)

AUTHOR

Karsten Ballueder [email protected]

COPYRIGHT

multibuf is part of the KBackup package and protected by the GNU GENERAL PUBLIC LICENSE, Version 2.